Electrolytic condenser vent



w. G. PONTIS ETAL 2,227,319 ELECTROLYTIC counmissa VENT Filed May 28, 1937 W|LL|AM G. PONTIS PAUL E KOEHL Y Patented Dec. 31, 1940 UNITED STATES ass-1.31s snscraoamc compasses vsm William G. Pontis and Ohio, to General Detroit, Mich a corporation of Delaware Paul I. Koehly, Dayton, Motors Corporation,

Application May :8. 1m, Serial No. 145,210

3Clairns.

This invention relates to electrolytic condensers and more particularly to means for venting the interior of the condenser upon an increase of internal pressure approaching the exploding point.

It is an object of the present invention to provide a blow-out plug as a venting means for excessive pressure within an electrolytic condenser.

Another object of this invention is to provide a method of seating a vent plug for electrolytic con. densers.

Another object is'to provide a releasable vent plug for an electrolytic condenser, by ntting a plug within an aperture so as to engage the walls of the aperture with sufilcient firmness to remain 5 in position for all normal pressures, but which plug is adapted to be unseated upon development of excessive pressure.

A further object is to provide a plug for closely fitting an aperture in a lid member for an elecgo trolytic condenser, which plug will be self securing due to the cooperative properties of lid material and plug, pressing the plug in place for all normal pressures, but which plug is adapted to be unseated upon development of excessive pressures. as A further object is to provide a closure member for vent hole in electroltyic condensers, that, when pressed into place, will be self seating to withstand normal pressures developed within the container, but that will unseat under excessive pressure conditions.

Further objects and advantages of the present invention will be apparent from the following descrlption, reference being had to the accompanying drawing wherein a preferred embodiment of the present invention is clearly shown.

In the drawing: a

P18. 1 is a side view of an electrolytic condenser embodying, the instant invention, partly in elevation and partly in section, with parts removed for cleamess. The view is indicated by the line 4 and arrows l--l 'of Fig.2. Y

Fig. 2 is a top plan view of the condense Fig. 3 is a vertical sectional view on a larger scale of a fragment of the condenser lid, showing the vent plug being unseated.

Fig. 4 is a similar view but showing the plug as being completely unseated.

Fig. 5 is an enlarged detail. view of the sealing plug in section, before pressing into place.

Fig. 8 is a bottom plan view of the venting plug means. Y

Electrolytic condensers in service, when sub- .iected to high voltage currents, undergo consider able temperature changes which result in expanll sion and contraction of the electrolyte. In some instances, due to various causes, pressures within the electrolytic condenser develop to the point at which-the unit may blow up, or explode. As a matter of safety, it has long been the practice to provide the sealed containers with venting means, which practice has customarily made use of a punctured membrane disposed over a passage-way, that is normally closed, but which opens up under extreme pressure conditions within the condenserg and thereby relieves the pressure with- 1 in. That form of vent is unsatisfactory, inasmuch as itmakes possible for leaks of the electrolyte, that results in an early failure of the cell, in that its capacity changes, or in that it becomes wholly useless. Following that leakage, or escape of elec- 1 'trclyte, corrosion of metallic parts and short circult of the elements are sure to occur.

The herein described venting means constitutes an improvement over any known venting means,

in that itoperates to maintain the cell completely sealed for all conditions of the condenser use below the danger point, but upon the development of excessive pressure unseals the container, so as to prevent blow-up or exploding.

With particular reference to the drawing ill indicates-a can or container within which a condenser unit is enclosed, and which can is provided with a flange I! at its open end, telescopically received by a ring member it, having an inwardly directed flange II secured within the body of a lid member it by moldingthe lid of moldable composition so as to partly embed the flange ll of the ring substantially as shown in Fig. 1. At the time of forming the lid II, it is also cast about anchorage portimis 2| provided by a number of terminal posts 22. The number and arrangement of the terminal posts 22, varies as the conditions warrant for adaptation in the electrolytic condenser unit. A sufiicient number of the binding posts 22 protrudethroughthe body of the lid ll. somewhat as indicated at 24, and make provisions for connection with a conductor tab 2!, leading to the electrodes of the electrolytic condenser. Thisis all illustrated in Fig.1 of the drawing, except that the electrodes of the condenser, have been omitted for clearness of illustration. The condenser can or container II, with a lidso constructed, is assembled and maintained in sealed or air tight relation, by means of solder applied at the juncture 2' of the ring it and a peripheral ribll, formed near the open end of the container.

. The venting means comprises an aperture through the lid of the container, and in the present. instance is exemplified by a counterbore, the smallerdiameter ll of which opens on the interior the lid, thus forming a plane like shoulder 44 at within specified limits, thus precluding the posthe juncture of the small and large bore portions. 'In the form of invention illustrated, a sealing member is provided that constitutes a cup ll,

substantially as illustrated in enlarged detail in Figs. 5 and 6.. The cup-like member 5| is provided with a flat bottom 52, and very slightly tapered flanged side walls ll. This cup-like plug is so fashioned that the peripheral edge 56 is slightly larger in over-all dimension than the portion of the flange joining the flat portion 52. In other words the side walls 54 flare outwardly very slightly as they progress from the flat wall 52. That is illustrated in an exaggerated fashion by the dot-and-dash lines in Fig. 5. The plug 5. is so fashioned as respects the portion 42 of the counterbore, that the peripheral edge 56 is very slightly oversized, thus necessitating that the plug il be press fltted within the aperture 42, As respects the plug, it is fabricated from material soft as compared with the material of the lid It, so as to have suflicieni; yielding properties to follow any generally irregular portions in the side walls of the counterbore, or so as to compensate for variation in the counterbore, under which circumstances the plug will then perfect the desired seal when pressed into place.

By "soft" as stated above, that quality of relative hardness is meant that it is slightly less than the surface or spin hardness of the composition forming the head. Under such conditions and properties, the plug, when pressed into place takes a dead set, by reason of the further drawing operation perfected by the sidewalls of the counterbore, as the plug is pressed into place. Suitable material for a plug of that character may be a zinc alloy, sheet lead, brass or aluminum, de-

pending on the nature of the electrolyte to be used. The material used for the plug should be one not subject to contamination or corrosion by the electrolyte.

When an electrolytic condenser fitted with one of these improved venting means is placed in service, the seating means will remain in position for all normal working conditions, but upon the development of excessive pressures within the container, then the increased pressure operating through the aperture ll will unseat the .plug in the manner suggested by Figs. 3 and 4,

that results in relieving the excessive pressure developed within the container.

The vent plug herein described is made of a material and of a shape'that compensates for normal variations in hole and plug sizes and at the same time maintains within definite limits the required tightness to fit. That, is for the purpose of controlling the venting of pressure sibility of explosion.

The foregoing is accomplished in the following manner: The plug being of cup-shape with the prss flt diameter located at the open end, away from the rigid bottom, together with the ductility of material lends itself readily to diameter variations in the hole into which it is pressed.

In this case where the plug is pressed into the lid of Bakelite or of other molded material, the hole size and shape is not substantially changed. Where the diameter of the plug is .to the large limit and the hole to the small limit, the action of pressing the plug into the hole is likened to that of a second drawing die operation, that reduces the plug diameter in relation to the hole.

The plug being soft, yields to diameter variations, taking a reduced diameter set. From here on the tightness of press fit is controlled by the thickness of material. To increase the tightness of fit, it is only necessary to increase the thickness of material.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In an electrolytic condenser, an electrolyte container having an end wall provided with an aperture therethrough adapted to serve as a vent, and means frictionally secured within the aperture normally sealing the vent, and said means comprising a drawn metal cup whose flange diameter is greater than the diameter of the aperture, and tends to bite into the walls of the aperture when subjected to unseating pressure from within.

2. The combination set forth in claim 1, in which the sealing means comprises a metal cup having an outwardly flaring rim that is press fltted into the aperture of the end wall so that the rim edge engages the wall of the aperture.

3. The combination set forth in claim 1, in which the sealing means comprises a dished member inserted in the aperture of the end wall, which member has been further deformed so that its edges frictionally engage the walls of the aperture.

WILLIAM G. PON'I'IS. PAUL l". KOEHLY. 

